Apparatus for determining melting points



Jan. 10, 1961 Filed Jan. 14, 1958 FIE]. I.

J- R- E. HOOVER APPARATUS FOR DETERMINING MELTING POINTS 2 Sheets-Sheet 1 INVENTOR JOHN R. E. HOOVER WiMmb/V ATTYS.

Jan. 10, 1961 J. R. E. HOOVER 2,967,424

APPARATUS FOR DETERMINING MELTING POINTS Filed Jan. 14, 1958 2 Sheets-Sheet 2 FIEL4.

m'vENroR: JOHN R. E HOOVER I 799m w w United States Patent APPARATUS FOR DETERMINING MELTING POINTS John R. E. Hoover, 624 Crescent Ave., Glenside, Pa.

Filed Jan. 14, 1958, Ser. No. 708,947

1 Claim. (Cl. 73-17) The present invention relates to new and useful improvements in apparatus for determining melting points and particularly melting points of various chemicals and the like.

The principal object of the present invention is to provide novel apparatus whereby the melting points of materials placed therein may be quickly, accurately and easily determined.

Another object of the present invention is to provide novel apparatus for determining melting points of materials wherein the various elements of the apparatus are readily accessible for adjustment, repair or replacement.

A further object of the present invention is to provide novel apparatus for determining the melting points of materials wherein the material is placed in a container immersed in an oil bath and means are provided for closely regulating and controlling the temperature of the oil bath.

A still further object of the present invention is to provide novel apparatus for determining the melting points of materials having the features and characteristics set forth above which is of relatively simplified construction, may be manufactured easily and cheaply, and is entirely eflicient and effective in operation and use.

These and other objects of the present invention and the various features and details of the operation and construction thereof are hereinafter more fully set forth and described with reference to the accompanying drawings, wherein:

Fig. 1 is a perspective view of apparatus made in accordance with the present invention;

Fig. 2 is a fragmentary perspective view of the upper end of the housing for the apparatus of the present invention and the removable stirring and heating unit for the material for which the melting point is to be determined with the unit removed from the housing;

Fig. 3 is a perspective view of a portion of the removable stirring and heating unit of the present invention;

Fig. 4 is an enlarged fragmentary transverse sectional view taken on line 4-4, Fig. 1;

Fig. 5 is a fragmentary sectional view taken on line 5--5, Fig. 4;

Fig. 6 is a fragmentary sectional view taken on line 6-6, Fig. 4, illustrating the supporting means for various elements of the present invention;

Fig. 7 is a transverse sectional view taken on line 77, Fig. 6; and

Fig. 8 is a schematic wiring diagram of the apparatus made in accordance with the present invention.

Apparatus for determining melting points made in accordance with the present invention comprises essentially a housing designated generally as 10 which is adapted to receive and support a removable heating and stirring unit 11. The heating and stirring unit 11, in turn, supports a transparent beaker 12 formed of glass or similar material containing an oil bath in which the material to be melted is immersed. The oil bath preferably is silicone oil and Patented Jan. 10, 1961 preferably the beaker is approximately three-quarters filled. In addition to having the material to be melted immersed in the oil bath, the beaker also contains heating means to heat the bath to any desired temperature and agitating or stirring means to insure a uniform temperature throughout the bath. Additionally, the housing 10 of the apparatus of the present invention contains means for controlling the temperature of the bath, means for controlling the rate of agitation of the bath, and viewing means for determining when the sample immersed in the bath has melted.

Referring more specifically to the drawings and particularly Figs. 1, 2 and 4 thereof, the housing 10 has a flat upper wall 13 which, in turn, has a generally circular opening 14 therein adjacent the front wall 15 of the housing within which the glass beaker 12 of the removable heating and stirring unit is received with the removable heating and stirring unit resting against and supported by the upper housing wall 13. The beaker 12 extends downwardly within the housing forwardly adjacent an arcuate shield 16 which is supported beneath the upper wall of the housing, for example, by means of a plurality of bolts 17. A viewing opening 18 is provided in the front wall 15 of the housing immediately in front of the beaker 12, as illustrated in Fig. 4, and a magnifying glass 19 or some similar viewer is mounted forwardly adjacent the viewing opening 18, for example, by means of adjustable mounting means designated generally as 20 supported from the front wall 15 of the housing, as illustrated in the drawings, so that the operator of the apparatus of the present invention may view the material immersed in the beaker to determine when the material changes from the solid state to the melted state.

In order to illuminate the material immersed in the beaker, a pair of light bulbs 21, 21 are provided within the housing supported by means of a bracket 22. The light bulbs are positioned adjacent opposite sides of the upper portion of the beaker in such a manner that .the material within the beaker is fully illuminated. The bracket 22 supporting the lights is adjustably secured to the interior of the front wall of the housing 15, for example, by means of a bolt 23 which also mounts the adjustable support for the magnifying glass, and the light bulbs 21, 21 are adjustably carried by the bracket 22, for example, as indicated at 24 in Fig. 4 to permit the light bulbs to be positioned in the desired relation with respect to the material in the beaker 12.

With reference now to Figs. 2, 3 and 4, the removable heating and stirring unit of the present invention comprises aninteriorly threaded upper cap member 26 to which is secured a mounting plate 27, a motor housing 28 and a motor support bracket 29. The mounting plate 27 is positioned within the cap 26 while the motor housing 28 and motor support bracket 29 are mounted adjacent to the upper surface of the cap 26 and are secured to the cap 26, for example, by means of a pair of bolts 31, 31 extending upwardly through these various elements, as shown in Figs. 4 and 7. The beaker 12 is adapted to be positioned within the cap portion 26 with the upper lip of the beaker in engagement with the mounting plate 27 and an externally threaded lower cap member 32 is provided which may be positioned around the beaker 12 in engagement with the lower edge of the upper lip thereof and threadedly secured to the upper cap member 26 to a short distance from the bottom of the beaker 12, for example, as illustrated in Figs. 2 and 4, and supported by a pair of conductors 35, 35 extending downwardly into the beaker from the mounting plate 27. Each conductor 35 extends through an insulating ferrule 36 in the mountingplate 27 and the upper end of-each conductor is threaded and has a pair of nuts 37, 37 adjacent opposite sides of the ferrule 36 to fixedly secure the conductor to the mounting plate and properly position the conductor and heating coil with respect to the beaker. Lead wires 38, 38 extend from each conductor 35 to aplug 39 secured to the lower surface of the motor housing 28 and the plug 39 is adapted to be electrically connected with a socket 40 carried by the upper Wall of the housing and interconnected with control-means (more fully described hereinafter) for controlling the temperature of the oil bath. The stirring means for stirring the oil bath to maintain a uniform temperature throughout the bath consists of an agitator blade 42 carried by a rotatable shaft 43 projecting downwardly through an enlarged opening 44 in the mounting plate 27. The shaft 43 is operable to be removably secured to the shaft 45 of an electric motor 46 carried by the mounting bracket 29 within the motor housing 28 so that upon energization of the electric motor 46 the agitator blade 42 is caused to rotate and stir the oil bath. As illustrated in Fig. 4, the agitator blade 42 is positioned upwardly adjacent the heating coil 34 within the beaker 12 and well below the level of the oil in the beaker. The electric motor 46 is the variable speed type and has a pair of electric conductors 4'7, 47 secured thereto and connected to the plug 39 so that speed control means (more fully described hereinafter) carried within the housing 10 may be used to control the speed of the motor and thus the rate of agitation of the oil bath. Access may be had to the motor 46 by removing the cover 48 from the motor housing 28. By the above construction, it will be observed that both the heating means and the agitating means 'are supported independently of the beaker 12 by the mounting plate 27 and may be readily removed from the beaker 12 for adjustment or repair.

In accordance with the present invention, the material for which the melting point is to be determined is inserted into a conventional capillary tube having a closed'lower end and an open upper end and one 'or more capillary tubes 50 containing the material may be inserted through openings in the upper cap member 26 with the lower end thereof immersed in the oil bath. To properly position the capillary tubes 50 within the oil bath, a supportplate 51 is carried by the mounting plate 27 and spaced 'downwardly a predetermined distance therefrom so that it will be positioned within the oil bath. The support plate 51 is interconnected with the mounting plate 27 by means of a pair of vertically extending tie rods 52, 52 secured, at their lower ends, to the support plate 51 andterminating at their upper ends in threaded sections threadedly received in the mounting plate 27. By this construction, the position of the support plate 51 vertically with respect to the mounting plate 27 may be adjusted. Additionally, a guide plate 53 is carried by the threaded portions of the tie rods 52, 52 and positioned relative to the support plate 51 by means of a pair of nuts 54, 54 carried by the threaded portion of each tie rod and engagingopposite sides of the guide plate 53. The mounting plate and guide plate each have a plurality of guide openings 55 and 56, respectively, therein through which the capillary tubes 50 may pass and the lower ends of the capillary tubes 50 are adapted to be received within indentations 57 formed in the upper surface of the support plate.

By the construction described above, a plurality of capillary tubes 50 may be passed through the openings in the upper cap member 26, mounting-plate 27 and guide plate 53 to a position wherein the lower ends of the capillary tubes 50 rest on the support plate. The material to. be melted is placed inthese capillary tubes and is directly visible to the user of the apparatus through the magnifying glass 19 and viewing opening 18. Thus, in order to determine the melting point of the material, the oil bath is heated as previously described, and the material is viewed and the temperature of the bath taken at the instant the material melts. In order to take the temperature of the bath, means are provided to support a thermometer 60 with its lower end immersed in the bath and resting in an indentation 58 in the support plate 51 immediately behind the indentations 57. To accomplish this, a guide tube 59 is fixedly secured to themounting plate 27 and projects upwardly therefrom through an opening in the upper cap member 26. The thermometer 60 is positioned within the guide tube 59 and projects downwardly through an opening in the guide plate 53 into engagement with the support plate. Thus, the temperature of the bath at the instant the material in the bath melts may be easily read on the thermometer.

The various control elements and accessory equipment for operating the apparatus of the present invention is contained within the housing 10. For example, an autotransformer 62 and rheostat 63 are mounted within the casing and interconnected with control knobs 64 and 65, respectively, for controlling, respectively, the temperature of the heating element 34 and the speed of the motor driven agitator 42. Elements 63 and 63 are electrically connected with the socket 40 by means of wires (not shown) so that when the removable heating and stirring unit 11 is placed in its proper position on the top of the housing 10, the heating coil and motor are electrically connected with the rheostats. In addition, a solenoid operated vibrator 66 having a permanent magnet therein is carried by the upper wall 13 of the housing 10, as illustrated in Figs. 2 and 4 and after the material to be melted is placed in the capillary tubes 50 the capillary tubes are positioned within the vibrator 66 and vibrated to cause the material to be forced down to the bottom portion of the capillary tubes 50. Operation of the vibrator 66 is controlled by a single pole single throw switch 67 mounted on the front face of the housing 10, as shown in Fig. l and a second switch 68 which, in the present instance, is a double pole single throw toggle switch, is also mounted on the front face of the housing for turning the apparatus on or off. When the capillary tubes are not in use they may be stored in a container 69 secured to the upper wall of the housing 10 as illustrated in Figs. 1 and 2.

With reference now to Fig. 8, there is illustrated schematically the wiring and control diagram for the apparatus of the present invention. As shown, the switch 68 for turning the apparatus on and off is placed in the main power line and when this switch is in the off position none of the elements of the present apparatus may be energized. The heating coil 34 is interconnected on one side by means of a lead wire 70 to one pole of the switch 68 and is interconnected on its other side through the lead wire 71 to the central terminal of the autotransformer 62. The autotransformer 62 is interconnected on one side to the lead wire 70 and on the other side to a lead wire 72 leading to the other pole of the switch 68. Thus, when the switch 68 is closed, the power supplied to the heating coil 34 may be controlled by means of the adjustable autotransformer 62. In a similar manner, the motor 46 is also connected to the switch 68 and contains the rheostat 63 within its circuit so that the current supplied to the motor 46 may be varied to thereby vary thev speed of the motor. The motor 46 is connected to one pole of the switch 68 through the lead wires 70 and 73 and is connected to the central terminal of the rheostat 63 by means of the lead wire 74. The outer terminal of the rheostat 63 is connected to the other pole, of the switch through the lead wires 75 and 76. A transformer 77, which may be a conventional /63 volt transformer, is connected between opposite poles of the switch 68 by means of lead wires 78 and 79. The transformer 77 is used to provide a source of low voltage for the vibrator 66 and for the lamps 21, 21. The lamps 23, 21 are connected in parallel across the low voltage side of the transformer while the vibrator 66 and the vibrator switch 67 are also connected to the low voltage side of the transformer so that the switch 67 may be used to control the operation of the vibrator 66.

In order to operate the apparatus of the present invention, one or more samples of the material for which the melting point is to be determined is placed in the capillary tubes 50 and the capillary tubes are then inserted into the vibrator 66 and vibrated for a short length of time so that the material is forced down to the bottom of the capillary tube. Thereafter, the capillary tubes are inserted through the openings in the upper cap member 26 into the oil bath contained in the beaker 12 with the base of the tubes 50 resting on the support plate 51. Thereafter, the motor 46 for the agitator 42 is energized and current is supplied to the heating coil 34 to increase the temperature of the oil bath in the beaker 12. The temperature of the oil bath is raised slowly and the material in the capillary tubes is observed by the operator of the machine through the magnifying glass 19 and sight opening 18. When it appears that the material in the capillary tubes 50 is close to its melting point the rate of increase of the temperature of the bath is slowed down by means of the control knob 64 and at the instant the material melts the temperature of the oil bath is read on the thermometer 60. By closely controlling the rate of increase in the temperature of the oil bath a very accurate determination of the melting point of the material may be obtained. Air blast cooling means or the like can be utilized, if desired, to increase the rate of cooling.

From the foregoing, it will be apparent that the present invention provides novel apparatus whereby the melting points of materials may be quickly, accurately and easily determined and wherein the various elements of 6 the apparatus are readily accessible for adjustment, repair or replacement.

While a particular embodiment of the present invention has been illustrated and described herein it is not intended to limit the invention to such a disclosure and changes and modifications may be incorporated and embodied therein within the scope of the following claim.

I claim:

Inapparatus for determining the melting point of a material placed therein comprising a housing and a removable heating and stirring unit adapted to be carried by said housing; a mounting member fixedly secured to said removable unit, a heating coil supported by said mounting member and spaced downwardly from said mounting member, stirring means including an agitator and drive means for the agitator carried by said mounting member, said agitator being spaced downwardly from said mounting member, a beaker, means interconnected with said mounting member operable to removably secure said beaker to said removable unit with said heating coil and agitator positioned within said beaker, a supporting plate interconnected with said mounting member projecting downwardly thereform to a position within said beaker, and means supported by said plate operable to contain a sample of the material for which the melting point is to be determined with said sample of material positioned within said beaker.

References Cited in the file of this patent UNITED STATES PATENTS 2,658,382 Vanderkamp Nov. 10, 1953 OTHER REFERENCES Singh: A New Melting Point Apparatus," J. Chem. Education, vol. 31, December 1954, pp. 646-647.

Towson and Mercer Ltd., Reflected Light Melting Point Apparatus, J. Scientific Instruments, vol. 26, Febru-' ary 1949, p. 47 (1 page). 

